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"Hudson, J"
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Multiple spillovers from humans and onward transmission of SARS-CoV-2 in white-tailed deer
Many animal species are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and could act as reservoirs; however, transmission in free-living animals has not been documented. White-tailed deer, the predominant cervid in North America, are susceptible to SARS-CoV-2 infection, and experimentally infected fawns can transmit the virus. To test the hypothesis that SARS-CoV-2 is circulating in deer, 283 retropharyngeal lymph node (RPLN) samples collected from 151 free-living and 132 captive deer in Iowa from April 2020 through January of 2021 were assayed for the presence of SARS-CoV-2 RNA. Ninety-four of the 283 (33.2%) deer samples were positive for SARS-CoV-2 RNA as assessed by RT-PCR. Notably, following the November 2020 peak of human cases in Iowa, and coinciding with the onset of winter and the peak deer hunting season, SARS-CoV-2 RNA was detected in 80 of 97 (82.5%) RPLN samples collected over a 7-wk period. Whole genome sequencing of all 94 positive RPLN samples identified 12 SARS-CoV-2 lineages, with B.1.2 (n = 51; 54.5%) and B.1.311 (n = 19; 20%) accounting for ∼75% of all samples. The geographic distribution and nesting of clusters of deer and human lineages strongly suggest multiple human-to-deer transmission events followed by subsequent deer-to-deer spread. These discoveries have important implications for the long-term persistence of the SARS-CoV-2 pandemic. Our findings highlight an urgent need for a robust and proactive “One Health” approach to obtain enhanced understanding of the ecology, molecular evolution, and dissemination of SARS-CoV-2.
Journal Article
Increased plant biomass in a High Arctic heath community from 1981 to 2008
The Canadian High Arctic has been warming for several decades. Over this period, tundra plant communities have been influenced by regional climate change, as well as other disturbances. At a site on Ellesmere Island, Nunavut, Canada, we measured biomass and composition changes in a heath community over 13 years using a point-intercept method in permanent plots (1995-2007) and over 27 years using a biomass harvest comparison (1981-2008). Results from both methods indicate that the community became more productive over time, suggesting that this ecosystem is currently in transition. Bryophyte and evergreen shrub abundances increased, while deciduous shrub, forb, graminoid, and lichen cover did not change. Species diversity also remained unchanged. Because of the greater evergreen shrub cover, canopy height increased. From 1995 to 2007, mean annual temperature and growing season length increased at the site. Maximum thaw depth increased, while soil water content did not change. We attribute the increased productivity of this community to regional warming over the past 30-50 years. This study provides the first plot-based evidence for the recent pan-Arctic increase in tundra productivity detected by satellite-based remote-sensing and repeat-photography studies. These types of ground-level observations are critical tools for detecting and projecting long-term community-level responses to warming.
Journal Article
المساقط المائية : طبيعة وثقافة
يتضمن الكتاب دراسة لعدد من الشلالات حول العالم، مستكشفا هذا الشكل من تضاريس الأرض المهدد بالزوال لأسباب عديدة تعود في كثير منها إلى النشاط البشري، ولذا فإنه يعد شكلا من أشكال التوثيق لها من زوايا مختلفة توزعت على اثني عشر فصلا. ويبين الكتاب طبيعة الشلالات وأشكال نشوئها جيولوجيا وتوزعها جغرافيا، وتأثير السياحة والنشاط الصناعي والعمران البشري عليها، دون إغفال الحديث عن تأثيرها في عالمي الأدب والفن بأنواعه، إلى جانب الحديث عن تلوثها وجفافها والخطر المحدق بما لا يزال منها على «قيد الحياة».لا يدور هذا الكتاب حول أهمية الماء بوصفه عاملا حيويا، بل حول شكل محدد من أشكال التضاريس المائية التي تترافق دوما مع الإثارة والمغامرة، عارضا على القارئ استكشافها بطريقة مختلفة، بانورامية إن صح التعبير، ولا يكتفي بالنظر إليها من زاوية واحدة، لذا فإن قراءة هذا الكتاب توازي في متعتها رحلة حقيقية إلى الشلالات، خاصة لما تحققه صور المناظر البديعة التي يزخر بها من لذة بصرية.
Book
Improved measurement of the shape of the electron
How round is the electron?
The electron is spherical — well, nearly. The standard model of particle physics predicts a slightly aspheric electron, with a distortion characterized by the electric dipole moment (EDM) that is far too small to be detected at current experimental sensitivities. However, some extensions to the standard model predict much larger EDM values that should be detectable. New experiments, using the dipolar ytterbium fluoride rather than spherical thallium, achieve the highest precision measurement of the EDM to date. At this new level of precision the EDM is consistent with zero, and the electron is indeed a sphere. This finding should help to constrain theories of particle physics and cosmology beyond the standard model.
The electron is predicted to be slightly aspheric
1
, with a distortion characterized by the electric dipole moment (EDM),
d
e
. No experiment has ever detected this deviation. The standard model of particle physics predicts that
d
e
is far too small to detect
2
, being some eleven orders of magnitude smaller than the current experimental sensitivity. However, many extensions to the standard model naturally predict much larger values of
d
e
that should be detectable
3
. This makes the search for the electron EDM a powerful way to search for new physics and constrain the possible extensions. In particular, the popular idea that new supersymmetric particles may exist at masses of a few hundred GeV/
c
2
(where
c
is the speed of light) is difficult to reconcile with the absence of an electron EDM at the present limit of sensitivity
2
,
4
. The size of the EDM is also intimately related to the question of why the Universe has so little antimatter. If the reason is that some undiscovered particle interaction
5
breaks the symmetry between matter and antimatter, this should result in a measurable EDM in most models of particle physics
2
. Here we use cold polar molecules to measure the electron EDM at the highest level of precision reported so far, providing a constraint on any possible new interactions. We obtain
d
e
= (−2.4 ± 5.7
stat
± 1.5
syst
) × 10
−28
e
cm, where
e
is the charge on the electron, which sets a new upper limit of |
d
e
| < 10.5 × 10
−28
e
cm with 90 per cent confidence. This result, consistent with zero, indicates that the electron is spherical at this improved level of precision. Our measurement of atto-electronvolt energy shifts in a molecule probes new physics at the tera-electronvolt energy scale
2
.
Journal Article
Peter Pan : an illustrated classic
The adventures of the three Darling children in Never-Never Land with Peter Pan, the boy who would not grow up.
Book
Consistent effects of pesticides on community structure and ecosystem function in freshwater systems
Predicting ecological effects of contaminants remains challenging because of the sheer number of chemicals and their ambiguous role in biodiversity-ecosystem function relationships. We evaluate responses of experimental pond ecosystems to standardized concentrations of 12 pesticides, nested in four pesticide classes and two pesticide types. We show consistent effects of herbicides and insecticides on ecosystem function, and slightly less consistent effects on community composition. Effects of pesticides on ecosystem function are mediated by alterations in the abundance and community composition of functional groups. Through bottom-up effects, herbicides reduce respiration and primary productivity by decreasing the abundance of phytoplankton. The effects of insecticides on respiration and primary productivity of phytoplankton are driven by top-down effects on zooplankton composition and abundance, but not richness. By demonstrating consistent effects of pesticides on communities and ecosystem functions and linking pesticide-induced changes in functional groups of organisms to ecosystem functions, the study suggests that ecological risk assessment of registered chemicals could be simplified to synthetic chemical classes or types and groups of organisms with similar functions and chemical toxicities.
The effects of pesticides on individual species could propagate into additional community-wide and ecosystem-level effects. Here the authors use a mesocosm experiment to test how a diverse array of herbicides and insecticides disrupt aquatic community structure and ecosystem function.
Journal Article
Global politics : applying theory to a complex world
\"Global Politics is an entry-level IR and Global Studies text that integrates historical context where necessary in the discussion of global issues and integrates the mainstream theoretical approaches within every chapter to provide students a rich and meaningful way to understand and critically analyze what is happening in the world today\"-- Provided by publisher.
Book
Unraveling the disease consequences and mechanisms of modular structure in animal social networks
Disease risk is a potential cost of group living. Although modular organization is thought to reduce this cost in animal societies, empirical evidence toward this hypothesis has been conflicting. We analyzed empirical social networks from 43 animal species to motivate our study of the epidemiological consequences of modular structure in animal societies. From these empirical studies, we identified the features of interaction patterns associated with network modularity and developed a theoretical network model to investigate when and how subdivisions in social networks influence disease dynamics. Contrary to prior work, we found that disease risk is largely unaffected by modular structure, although social networks beyond a modular threshold experience smaller disease burden and longer disease duration. Our results illustrate that the lowering of disease burden in highly modular social networks is driven by two mechanisms of modular organization: network fragmentation and subgroup cohesion. Highly fragmented social networks with cohesive subgroups are able to structurally trap infections within a few subgroups and also cause a structural delay to the spread of disease outbreaks. Finally, we show that network models incorporating modular structure are necessary only when prior knowledge suggests that interactions within the population are highly subdivided. Otherwise, null networks based on basic knowledge about group size and local contact heterogeneity may be sufficient when data-limited estimates of epidemic consequences are necessary. Overall, our work does not support the hypothesis that modular structure universally mitigates the disease impact of group living.
Journal Article